Preparation and Properties of CsPbX3(X=Br, I) Quantum Dots

The all-inorganic perovskite quantum dot CsPbX3 (X = Cl, Br, I) exhibits unique optical properties enabled by its bandgap tunability. CsPbX3 quantum dots with varying I⁻ doping ratios were synthesized via ligand-assisted reprecipitation (LARP). Appropriate I⁻ doping can effectively modulate the lattice parameters of the quantum dots, resulting in a redshift of the absorption band edge and a narrowing of the optical band gap in the ultraviolet-visible absorption spectrum. Excessive I⁻ doping induces a 91% reduction in fluorescence quantum yield due to lattice distortion. Transmission electron microscopy (TEM) and X-ray diffraction (XRD) analyses confirmed that the quantum dot size was highly uniform and the monoclinic crystal phase remained stable. Ultraviolet-visible diffuse reflection spectroscopy and fluorescence spectroscopy elucidated the synergistic effects of quantum confinement and exciton recombination dynamics. This study underscores the significant impact of I⁻ doping on Br-based perovskites, providing a foundation for the rational design of heterojunctions in perovskite systems.